Re: [Buildroot] [PATCH v2 02/11] package: elf2flt: Update RISC-V 64-bits support

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello Damien, Hello Niklas,

On Mon, 30 May 2022 12:38:27 +0900
Damien Le Moal via buildroot <buildroot@buildroot.org> wrote:

> From: Damien Le Moal <damien.lemoal@wdc.com>
> 
> Remove the old elf2flt 0002-elf2flt-add-riscv-64-bits-support.patch
> patch file for riscv64 architecture and replace it with 3 patches:
> 
> (1) The first patch fixes the data section alignment
> (2) The second patch fixes a bug with the handling of the eh_frame
>     section causing text and data section overlap problems.
> (3) The third patch adds a simpler riscv64 flat bin relocation support.
> 
> These 3 patches are submitted to the upstream elf2flt project as pull
> request #22:
> 
> https://github.com/uclinux-dev/elf2flt/pull/22

We are seeing an issue with this patch applied: it segfaults when
linking binaries on the m68k architecture.

To be fully clear, when we use the current version of elf2flt in
Buildroot (2021.02) + patch 0001-elf2flt-handle-binutils-2.34.patch +
patch 0002-elf2flt.ld-reinstate-32-byte-alignment-for-.data-sec.patch,
we have the following failure:

  /home/thomas/buildroot/outputs/m68k/host/m68k-buildroot-uclinux-uclibc/bin/elf2flt: ERROR: text=0x7db78 overlaps data=0x6b940 ?

which already existed *prior* to applying your patch.

However, as soon as we add
0003-elf2flt-fix-.eh_frame-section-handling.patch into the patch series
applied to elf2flt, we get:

  ld (ld-elf2flt): /home/thomas/buildroot/outputs/m68k/host/m68k-buildroot-uclinux-uclibc/bin/elf2flt terminated with signal 11 [Segmentation fault], core dumped

Our friend gdb gives us some hint on where the segfault occurs:

#0  0x000055ebfc7524e0 in add_com_to_bss (bss_len=19112, number_of_symbols=3869, symbol_table=0x55ebfd601d50) at elf2flt.c:273
273         if (strcmp("*COM*", symbol_table[i]->section->name) == 0) {

Of course, we're not sure if the error "ERROR: text=0x7db78 overlaps
data=0x6b940 ?" is fixed by your patch and a later problem causes the
segfault, or if your patch causes the segfault in the first place.

Please note that if we revert both
32f93b0ef2c602dfa1f5b243ba865d5b16e2fa33 and
65d78dcfeb8b2eafaebe2d0c3c8c42e7e85f46ac in Buildroot, we have a
working elf2flt for m68k.

Do you have any idea?

Thanks a lot!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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